Hey there, I believe I can tell you about the same story happens in MC. Actually, this doesn't seem like the differences in class strength, but rather individual differences between you and the players you face. As all known, in arena environment, MC players have more advantages because of their range-based skills. It can be easily proof as shown in ss of current arena ranking. Also the winning rate of them are higher than other players.
There's no absolute fairness in this world, maybe it's just because they have better equipments, more books than you, or maybe they have better team configurations and spend more time on practicing.
There are many factors that may affect the in-game experience, and subjective feeling is the most inaccurate way to judge. I believe that the developer team can get more objective figurations than your feeling in their background data.